Acute Corneal Hydrops in Crosslinked Corneas

To characterize incident acute corneal hydrops (hydrops) in keratoconus after corneal crosslinking (CXL).

Retrospective review of patients with hydrops after CXL seen at Mass Eye and Ear between 2016 and 2022.

Of 1271 CXL procedures performed during the study period, 6 eyes (0.5%) of 6 patients (0.7%) experienced hydrops after CXL. Four were male, with a mean age of 25.8 ± 10.2 years (range: 13-42 years). All cases were considered severe by Amsler-Krumeich classification, with average steepest keratometry of 91.4 ± 15.0 D and average thinnest pachymetry of 335.8 ± 46.1 μm. In 5 of the 6 cases, transepithelial CXL was performed instead of epithelium-off CXL, usually because of insufficient corneal thickness for a safe epithelium-off procedure. Hydrops occurred as soon as 6 weeks after crosslinking and up to 4 years later (median: 1.8 years, interquartile range: 0.4-2.6 years). Five of the cases included minor trauma (eye rubbing or contact lens manipulation). Eyes experiencing hydrops tended to exhibit a greater increase in keratometry and decrease in corneal thickness after crosslinking compared with the contralateral eye, which also underwent crosslinking, although the study was insufficiently powered to detect significance. However, hydrops still occurred in cases demonstrating corneal flattening after hydrops.

Advanced keratoconus severity and trauma-through eye rubbing or contact lens wear-are consistent themes of patients experiencing hydrops after CXL. As the condition may present years after the procedure, patients should continue to be followed routinely for years even with demonstrated keratometric flattening.